Re: [PATCH 1/3] drm/msm/disp/dpu1: allow reservation even if dspps are not available.
From: Dmitry Baryshkov
Date: Tue Jan 17 2023 - 22:28:26 EST
On 18/01/2023 05:24, Kalyan Thota wrote:
-----Original Message-----
From: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
Sent: Tuesday, January 17, 2023 10:10 PM
To: Kalyan Thota (QUIC) <quic_kalyant@xxxxxxxxxxx>; dri-
devel@xxxxxxxxxxxxxxxxxxxxx; linux-arm-msm@xxxxxxxxxxxxxxx;
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Subject: Re: [PATCH 1/3] drm/msm/disp/dpu1: allow reservation even if dspps are
not available.
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On 17/01/2023 18:35, Dmitry Baryshkov wrote:
On 17/01/2023 18:21, Kalyan Thota wrote:
if any topology requests for dspps and catalogue doesn't have the
allocation, avoid failing the reservation.
This can pave way to build logic allowing composer fallbacks for all
the color features that are handled in dspp.
Signed-off-by: Kalyan Thota <quic_kalyant@xxxxxxxxxxx>
---
drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
index 73b3442..c8899ae 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
@@ -343,7 +343,13 @@ static bool
_dpu_rm_check_lm_and_get_connected_blks(struct dpu_rm *rm,
return true;
idx = lm_cfg->dspp - DSPP_0;
- if (idx < 0 || idx >= ARRAY_SIZE(rm->dspp_blks)) {
+
+ if (idx < 0) {
The change doesn't correspond to commit message.
+ DPU_DEBUG("lm doesn't have dspp, ignoring the request %d\n",
lm_cfg->dspp);
+ return true;
+ }
+
+ if (idx >= ARRAY_SIZE(rm->dspp_blks)) {
DPU_ERROR("failed to get dspp on lm %d\n", lm_cfg->dspp);
return false;
}
If you'd like to remove duplicate for the (idx >= ARRAY_SIZE) check,
I'd suggest dropping the second one
I've misread the patch. However I don't see, why would one request DSPP_NONE
while specifying topology->num_dspp. I think that you are trying to put additional
logic into a function that should just check for the available resources.
The link is specified in the catalogue.
For example:
LM_BLK("lm_0", LM_0, 0x44000, MIXER_SC7180_MASK,
&sc7180_lm_sblk, PINGPONG_0, 0, DSPP_0), --> This LM has DSPP attached
LM_BLK("lm_2", LM_2, 0x46000, MIXER_SC7180_MASK,
&sc7180_lm_sblk, PINGPONG_2, LM_3, 0), --> no DSPP
LM_BLK("lm_3", LM_3, 0x47000, MIXER_SC7180_MASK,
&sc7180_lm_sblk, PINGPONG_3, LM_2, 0), --> no DSPP
For the above example, num_dspps will be 1 which is nonzero. But if a request comes on second interface and if there are no dspps then we are not failing the reservation of data path as color features can be offloaded to GPU.
Idx for LM_2 and LM_3 will be -1 for above case hence the check not to fail reservation.
topology->num_dspp previously was filled based on encoder type, since we want to move away from encoder checks, we are now passing it same as LM number. If there are dspps available we will allocate,
in case of non-availability then we are not failing the datapath reservation so that composer fallbacks can be implemented.
As I wrote, num_dspps should be filled correctly (by the
dpu_get_topology) to request DSPP for CTM-enabled CRTCs and to set the
field to 0 if CRTC doesn't have CTM enabled.
Then RM code should adhere to the num_dspps passed. It must return an
error if it can not fulfil the requirements. Also if no DSPPs are
requested, RM should prefer non-DSPP-enabled LMs.
--
With best wishes
Dmitry